Butter a square pan and line with parchment paper for easy removal of set fudge. Set aside.
In a microwave safe 2 quart bowl, heat chocolate chips & sweetened condensed milk, on high for 1 minute. Let sit for 1 minute, then stir to combine. If needed, heat an additional 30 seconds. Stir until chips are completely melted and chocolate is smooth.
Stir in 1 teaspoon vanilla extract. Pour fudge into prepared pan. Let fudge cool completely before cutting into 1 inch squares.
Store in an airtight container. Fudge does not need to be kept refrigerated.
note: you can place in the refrigerator for 1 hour to speed up the process.